High frequency stabilizer



Aug. 23, 1932. L. A. HYLAND HIGH FREQUENCY STABILIZER 2 Sheets-Sheet 1 Filed May 6, 1929 INVENTOR.

ATTORNEY flaw/um a, BY

Aug. 23, 1932. A. HYLAND HIGH FREQUENCY STABILIZER 2 Sheets-Sheet 2 Filed May 6, 1929 INVENTOR.

ATTORNEY.

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Patented Aug. 23, 1932 stars at s PAQVENT orFicE tawanncn A. nrnann, or WASHINGTON, DISTRICT or COLUMBIA, assrelvon To wrann nanro, Inc, or New YORK, N, Y., A CORPORATION or DELAWARE HIGH FREQUENCY STABILIZER [a lication filed May 6, 1929. Seria 1 No.'360,906.

My invention relates broadly to the fre quency control of high frequency systems from a remote source. 7

One of the objects of my inventionis to provide a remote control system for stabiliz ing the frequency of a radio transmitter.

Another object of my invention is to provide a remote control system wherein the fre- V quency characteristics of a remotely located circuit are maintained substantially constant.

Still another object of my invention isto provide a frequency control system wherein t frequency of the energy emanated from a transmitting station is automatically'controlled in accordance with the frequency from a remotely located constant frequency station.

'ther and furtherobjects of my invention reside in certain circuit arrangements for obtaining the desired operating characteristics, a better understanding of which can be had from th specification followingand the,

accompanying drawings, wherein:

Figure 1 is a schematic circuit diagram showing the remote standard frequency control station and Fig. 2 is a schematic circuit diagram showing a high frequency transmit-' ter the f equency characteristics of which arecontrolled in accordance with my invention.

My system for the remote control of high frequency circuits employs a synchroscope adjusting arrangement somewhat similar to that shown and described in my copending application Serial No. 350,053, filed March 26,- 1929, entitled High frequency stabilizers now Patent No. 1,822,812, issued September 8, 1931, and my copending application Serial No. 359,381, filed April 30, 1929.

A suitable mechanically vibratile element serves as a standard of frequency. Fig. 1 of the accompanying drawings shows element 7 a electric crystal, however any suitable means may be employed as an initial frequency standard. Element 7 is connected with the input circuit of thermionic tube oscillator 6. The output circuit of thermionic tube 6 is connected with the input circuit of thermionic tube rectifier 8. The output circuit of thermionic tubeirectifier v8 is connected with a multi vibrato'r or" subharmonic circuit comprising thermionic tubes 9 and 10. This circuit is adapted to produce subharmonics of the frequency of the exciting source as describedby Messrs. Lewis M. Hullxand James K. Clapp, in Proceedings of the Institute ofiRadio Engineers, volume 17pages 252-271, February, 1929, inan article entitled A convenient method for referring secondary frequency standards to a. standard time interval. I

Any suitable arrangement may be employed to produce the subharmonic frequencies other than thearrangement illustrated. In the arrangement shown it is possible to produce a subharmonic of a value one-fiftieth of thefrequency value of the exciting source.

' eration upon a number of factors, primarily the asymmetry of thermionic tubes 9 and 10,

or, the equivalent, the asymmetry of their circuits. I Th-ermionic tubes having unlike characteristics may be employed or the effective characteristics of like tubes caused to vary by means of resistors30, 31 connected with their respective anodes. These resistors may be of values having ratios substantially50 to 1 or other ratio as determined from experiment.

Condensers 32, 33contribute to the operating characteristics and assist in establishing the desired condition for producing submultiples of the exciting energy. By exciting energy is meant the energy from the output circuit of thermionic tube rectifier 8. Thermionic tube 8 may be of any suitable type other than that shown such as, for instance, of the shield anode type or shield control electrode type. This may be desirable to prevent interaction from the multivibrator as pointed out in the article by Hull and Clapp referred to above. Again, I desire it to be known that it is not essential to my invention that the Inultivibrator illustrated in the accompanying drawings be employed. Any suitable 'cies may be employed.

The transmitter proper comprises thermionic tube oscillator 26 having input and outsystem for producing 'submultiple frequenput circuits for producing oscillations of high frequency energy. The output of thermionic tube 26 is delivered to the input circuit of thermionic tube amplifier 27. The output of thermionic tube 27 is delivered to space radio radiating system 29 as shown, or may be delivered to any desired load circuit such as a wired radio system. Thermionic tube 13 is fundamentally a rectifier having a divided input circuit comprising coils 11 and 12. Coil 12is in inductive relation to the output circuit of thermionic tube 27 or in other manner related with the energy in this circuit. Coil 11 is similarly associated with constant frequency oscillator standard 6.

15 Energy from the output of amplifier 27 and energyfrom oscillator 6 is coupled into the input circuit of thermionic tube rectifier 13. The output circuit of rectifier 13 comprises coils 11 1 and '15 wherein is present the beat frequency of thedifli'erence of the frequencies of oscillator 6 and the output of amplifier 27. The output energy of subharmonic producer 9-10 is connected with win ding 20 of trans :former 21. Winding 22 of transformer 21 25 is connected with thermionic tube 23. The

output circuit of thermionic tube 23 comprises coils 16 and 17 and phase-splitting circuit 18, 19. Coils 16 and 17 are positioned substantially at right angles to each other and suitably supported on a pivot which allows free movement of the coils.

Coils 14 and 15 arepositioned substantially as schematically illustrated, in inductive relation to coils 16-17. Coils 16-17 cooperatively actuate condenser 25 by means of mechanical connection 24 or'in any suitable -manner. My copending application Serial *No. 350,053, now Patent No. 1,822,812, issued September 8, 1931, describes the adjustable :4 frequency control in more detail.

The operation may be summed up as fol- "lows: Suppose, for example, it is desired to generate and transmit energy from oscillator 26 having a frequency of 510 kilocycles. The power rating of thermionic tube 26 may be of the order of 10 kilowatts. Mechanically vibratile element 7 may be chosen to have a fundamental frequency of 500 'kilocycl'es. The energy from oscillator 6 transferred to the input circuit of thermionic tube 13 would have a frequency of 500 kilocycles. .The frequency of the energy from oscillator 26 trans ferred to the input circuit of thermionic tube 13' would have a frequency of 510 kilocycles. In the output circuit of thermionic tube .13 comprising coils 14: and 15, a beat fre- :quency of 10 kilocycles is present. The frequency of the energy transferred from oscillator 6 to thermionic tube 8 will be 500 kilocycles. Selecting the 50th submultiple frequency of this value .means that the input clrcuit of thermionic tube 23 will have a current having a frequency'of 10 kilocycles. 'Thecurrent of 10 kilocycle frequency from i'fithermionic tube 23 energizes movable coils 16-17 at this frequency. Since the excitation of coils 14-15 is by current of like fre quency value, no torque is exerted upon coils 16-17.

If, however, the frequency of the energy from oscillator 26 should reduce to 509.5 kilocycles instead of the desired value of 510 kilocycles, the energization of coils 14-15 would be at 9.5 kilocycles instead of 10 kilocycles. This difference would be sufficient to produce a torque which would act upon coils 16-17 moving the same from their normal position. This motion is in turn transmitted by suitable means, represented at 21, to any suitable frequency controlling device herein represented as condenser 25. The motion transmitted to condenser 25 may be sufficient to correct the adjustment of frequency, as in the example above, and to increase the frequency characteristics of the oscillatory circuit to the amount of 500 cycles or .5 kilo cycle to reestablish the generation of the 510 kilocycle energy. In like manner, should the frequency from oscillator 26 increase to 510.5 kilocycles instead of remaining at 510 kilocycles, the beat frequency would be .5 lrilocycle. Since the difference between the 9.5 ltilocycle beat frequency in coils 1 1-15 and the 10 kilocycle frequency in coils 16-17 is 500 cycles, a torque would be exerted upon movable coils 16-17 causing a displacement of the movable coils. From first consideration it would seem that the 500 cycle increase of frequency or the 500 cycle decrease of frequency would effect a similar displacement of the movable coil and that no stability results. It must be remembered that the beat frequency in coils l t-15 in the first instance was 9.5 kilocycles, but in the latter instance is 10.5 kilocycles. I

The frequency of the energy in coils 16-17 remains constant at 10 kilocycles. Between the frequency of energy in coils 16-17 and the frequency of the energy in coils 1 l -l5, in the first instance, the difference was .5 ltilocycle. l he solution. rests on the fact that in the former instance the frequency of the energy in coils 14-15 was 9.5 kilocycles While in the latter instance the frequency is 10.5 kilocycles. t is obvious that an equal torque will be produced in either instance. It is also obvious that the displacement of the movable coils will be of a like amount. It will be observed, however that the displacement in the first instance will be in the opposite direction to the displacement in the latter instance. Movable coils 16-17 are not set at Zero beat but are moved an appreciable displacement from such position. This allows the movement in either direction. When the frequency of the energy in coils 1 115 increases, coils 16-17 will be moved in a given direction. l/Vhen the frequency decreases, coils 16-17 will be moved in the opposite direction.

prises any suitable energy collecting system,

herein represented as directional coil antenna 7a, which is connected with a suitable high frequency amplifier circuit herein represented by thermionic tube 6a. Coil antenna 7a serves to collect the high frequency energy of constant frequency from the transmitter illustrated in Fig. 1. High frequency amplifier 6a amplifies the incoming signaling energy which, in the example chosen, isof the order of 510 kilocycles. Thisenergy of 510 kilocycle frequency is delivered to the input circuit of thermionic tube rectifier 8a. The output of rectifier 8a is associated with a subharmonic producer 9a10a. Resistors 30a,

31a and condensers 32a, 33a serve to produce the necessary asymmetry of thermionic tubes 9a, 10a. The output is connected with winding 20a of transformer 21a. The 51st subharmonic of the frequency from rectifier 9a is selected which is of the order of 10 ki1ocycles. Thermionic tube 23a amplifies the energy of this frequency and transfers the same to movable coils 16a-17a through phase-splitting circuit 18a'19a. The transmitter, the frequency of the emanating energy from which is to be controlled, comprises principally thermionic tube oscillator 26a, thermionic tube amplifier 27a and radiating or load circuit 29a. The frequencyof the energy from the transmitter may be selected as of the order of 500 kilocycles. ergy beats with the received energy of 510 kilocycles'and in the output circuit of rectifier 13a the beat frequency is of 10 kilocycles, being the difference between the two.

Since this is also the 51st subharmonicor submultiple frequency of the received energy, movable coils 16a l7a remain steady. Should the frequency of oscillator 26a increase or decrease from the value of 500 kilo cycles, a rotating field between coils l4za'l5a and 16a17a.would be created and a torque exerted upon movable coils 16a17a. The movement of coils 17a and 16a would be transmitted to frequency controlling element 25a which would be moved to change the frequency characteristics of the circuit restoring the same to the original frequency of 500 kilocycles.

Many different values may be chosen for the frequencies employed. For instance at the master transmitting station illustrated in This en- I rately maintained constant.

Fig. 1, the energy in the input circuit of thermionic tube 13 may be harmonic frequencies -of'the energy from oscillators 6' and 26.. Ac- .cordingly'any submultiple frequency may be selected from source 6. In like manner the frequencies chosen at the remote transmitting station will be governed accordingly. .The

beat frequency energy may be supplied to the movable coils and the energy of submultiple frequency supplied to the stationary coils. Any suitable typeof thermionic tubes may .be employed. "Additional stations maybe controlled by either transmitting station.

Thus, in the example given, the. energy radiated from antenna 29a of transmitter 26a, era has a frequency of 500 kilocycles. This 500 'kilocycle frequency may be employed to serve as a standard frequency for additional transmitters.

If desired the 500 kilocycle energy received may be employed instead of source7, shown in Fig. 1, thereby establishing a'definite and uniform frequency separation between the frequency of the energy radiated from the Suppose that element '7,

two transmitters. shown in Fig. 1, is replaced by a suitable energy collecting system receiving the energy from transmitter 26a27a, shown in Fig. 2. The 500 kilocycle energy would beat with the energy of transmitter 2627 which is 510 kilocycles producing a beat frequency of 10 kilocycles as formerly when element 7 was employed. Since constant frequency element 7 is not employed the frequency of the energy D radiated from antenna 29 would be governed or controlled by the frequency of the energy received from transmitter 26a-270;; The

condition can now'be realizedwhereby one statlon acts as a standard frequency station for another station and also where each station controls the other station. The primary I requirement is that broadcasting stations, and

code stations as well, be separated by a definite frequency band. The regulatory authorities of the United States insist that the frequency of each station be controlled within reasonable limitsas predetermined according to geographical and frequency separation. Sincethe geographical separation is already established all that remains is that each station 7 operate on the proper frequency. In the present system of my invention it is obvious that any number of stations may be interrelated to effect the necessary frequency separation at all times. For instance, in the example given where element 7 is removed and the energy from transmitter 26a27a is employed to control the frequency of the energy from transmitter 2627, the frequency separation between the radiated energy from the two transmitters isautomatically and accu- Since the frequency separation is fundamentally the only consideration of importance in frequency allocation, it is obvious that from a constant frequency station all other stations maylbe controlled in that they will. automatically re- 'main separated a given frequency range. This is especially valuable in the broadcast band of'frequencies.

As an example of the effectiveness of the remote control of frequency according to my invention the following frequency relations are given: 1 i 1 Kilocycles Master station constant frequency element 400 Master station transmitter frequency 410 Master station beat frequency 10 Master station -10th subiiarmonic frequency 10 Station 'A Station receiver frequency adjustment 410 Station transmitter frequency adjustmenL 420 Station beat frequency adjustment 10 Station 41st subha monie frequency adjustment" 10 Station 13 Station receiver frequency adjustment 420 Station transmitter frequency adjustment- 430 Station beat frequency adjustment 10 Station 42nd sublmrmonic frequency adjustment 10 portion. This automatically prevents heterodyne between the stations since the frequency difference is determined by the frequency change ofthe master station. Any number of stations may be interlinked in this manner and the frequency separation between the stations automatically controlled within the desired limits of frequency.

It is obvious that the frequency control arrangement of my invention may be employed to control receiving apparatus in a manner similar to'that shown and described. Irealize that many modifications of my invention are possible. Any satisfactory relation of received to transmitted frequency may be employed as well as any system for producing submultiple frequencies. It is to be understood that the embodiments of my invention are not to be restricted by the foregoing specification or by the accompanying drawings but only by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a radio system, a standard transmitting station comprising a transmit-ting antenna, a source of power oscillations connected to said antenna, a source of oscillations of standard frequency, frequency stabilizing means for maintaining the frequency of said power oscillations equal to said standard frequency, a controlled station geographically separated from said standard station comprising a receiving antenna and an independent transmitting antenna, said receiving antenna being adapted to receive energy from said transmitting antenna of said standard station, a second source of power oscillations connected to-said independent transmitting antenna, frequency stabilizing means for -maintaining the frequency of said second source of power oscillations in a determined relation with reference to the oscillations rerceived on said receiving antenna from said standard station, each of said frequency stabilizing means comprising tuning means for controlling the frequency of said power oscillations, means for producing sub-har- 7 monies of said standard frequency and said received oscillations respectively, and means actuating said tuning element.

2. In a radio system, a plurality of stations geographically separated from each other, each of said stations'comprising a transmitg ting antenna and a receiving antenna, receiving apparatus at each of said stations adapted to receive oscillations from a remote transmitting antenna, and frequency stabilizing means at each of said stations for maintaining a fixed frequency relation between the frequency of oscillations received at said station and the frequency of oscillations trans- .mitted from said station, said frequency .StflblllZiQg means comprlsing tuning means for controlling the frequency of said power oscillations, means for producing sub-harmonics of the received oscillations, and means responsive to the difference between one of said sub-harmonics and the beat frequency between said power oscillations and said received oscillations for actuating said tuning element.

3. In a radio system, a plurality of stations geographically separated from each other, 1% each of said stations comprlsing a transmitting antenna and a receiving antenna, receivlng apparatus at each of sald stations adapted to receive oscillations from a remote transmitting antenna, and frequency stabilizing means at each of said stations for main taining a fixed frequency relation between the frequency of oscillations received at said station and the frequency of oscillations transmitted from said station, said frequency 315 stabilizing means comprising tuning means for controlling the frequency of said power oscillations, means for producing sub-harmonies of the received oscillations, and means responsive to the difference between one of sub-harmonics and the beat frequency between said power oscillations radiated from said transmitting antenna and said received oscillations for actuating said tuning element.

LAWVRENCE A. HYLAND. 

